1. Field of the Invention
This invention relates to drain valves used in aircraft. This drain valve normally is opened when the plane is on the ground, and in flight it automatically closes as the aircraft reaches a normal flying altitude. It opens when drain water is introduced into the valve and closes when drainage is complete.
2. Background Discussion
In large commercial aircraft, water is normally carried for both the crew and passengers. In flight this water is used for drinking and personal hygiene, and the waste water is discharged into the atmosphere. Normally, the cabin for crew and passengers is pressurized, and the discharge of the waste water must be done in a manner that minimizes loss of cabin pressure when the aircraft is at high altitudes. It is also desirable to insure that the drainage system for this water has been completely drained when the aircraft is on the ground to avoid the water freezing and clogging the drainage system with ice.